What you should know about storage-class memory

Red Hat Enterprise Linux 8.6 LPAR mode

Storage-class memory (SCM) is accessed, in chunks called increments, through extended asynchronous data mover (EADM) subchannels.

The LPAR on which your Linux® instance runs must be configured to provide SCM.
  • At least one EADM subchannel must be available to the LPAR. Because SCM supports multiple concurrent I/O requests, it is advantageous to configure multiple EADM subchannels. A typical number of EADM subchannels is 64.
  • One or more SCM increments must be added to the I/O configuration of the LPAR.

In Linux, each increment is represented as a block device. You can use the block device with standard Linux tools as you would use any other block device. Commonly used tools that work with block devices include: fdisk, mkfs, and mount.

Storage-class memory is useful for workloads with large write operations, that is, with a block size of 256 KB or more of data. Write operations with a block size of less than 256 KB of data might not perform optimally. Read operations can be of any size.